Lateral WSe₂ Homojunction through Metal Contact Doping: Excellent Self‐powered Photovoltaic Photodetector

Abstract

Here an IR‐heating chemical vapor deposition (CVD) approach enabling fast 2D‐growth of WSe2 thin films is reported, and the great potential of metal contact doping in building CVD‐grown WSe2‐based lateral homojunction is demonstrated by contacting with TiN/Ni metals in favor of holes/electrons injection. Shortening nanosheet channel to ≈2 µm leads to pronounced enhancement in the performance of diode. The fabricated WSe2‐based diode exhibits high rectification ratios without the need of gate modulation and can work efficiently as photovoltaic cell, with maximum open circuit voltage reaching up to 620 mV and a high power conversion efficiency over 15%, empowering it as superb self‐powered photodetector for visible to near‐infrared lights, with photoresponsivity over 0.5 A W−1 and a fast photoresponse speed of 10 µs under 520 nm illumination. It is of practical significance to achieve well‐performed photovoltaic devices with CVD‐grown WSe2 using fab‐friendly metals and simple processing, which will help pave the way toward future mass production of optoelectronic chips.

Self-Driven Gr/WSe2/Gr Photodetector with High Performance Based on Asymmetric Schottky van der Waals Contacts

“…Figure d shows the Raman and PL spectra of the multilayer WSe 2 and Gr. The Raman spectrum exhibits characteristic peaks of multilayer WSe 2 with in-plane vibration of the E 2g 1 mode located at 249.1 cm –1 , out-of-plane vibration of the A 1g mode located at 258.0 cm –1 , additional peak of the B 2g 1 mode at 309.2 cm –1 , and three combined peaks at 358.7, 370.7, and 393.4 cm –1 . The two characteristic peaks of multilayer Gr were located at ∼1583.2 cm –1 (G band) and ∼2722.3 cm –1 (2D band).…”

Optical Enhancement of Indirect Bandgap 2D Transition Metal Dichalcogenides for Multi‐Functional Optoelectronic Sensors

“…utilized relatively thick multilayer WSe 2 nanosheets (≈10–20 layers) and employed TiN and Ni as hole/electron injection contacts to fabricate lateral heterojunction devices. [ 111 ] The resulting WSe 2 diode demonstrated in Figure 4e shows a high rectification ratio and efficient photovoltaic operation. It exhibited a maximum V OC of 0.62 V, a power conversion efficiency exceeding 15%, and served as a self‐powered photodetector for visible to NIR wavelength.…”

“…(Inset: Scanning Electron Microscope image of the device). Reproduced with permission [111]. Copyright 2023, Wiley-VCH.…”

Asymmetric contact-induced selective doping of CVD-grown bilayer WS2 and its application in high-performance photodetection with an ultralow dark current

“…These methods encompass local electrostatic gating, 17 chemical doping, 18 carrier adjustment through plasma treatment 19 and carrier injection using uneven metal contacts. 20,21 WS 2 is a member of the TMD family and has been identified as an excellent candidate for optoelectronic applications due to its high stability, high carrier mobility and potential for mass production. 22,23 There have been reports on WS 2 -based photodetectors in the visible spectrum using monolayer, few layer and multilayer WS 2 .…”

“…These methods encompass local electrostatic gating, 17 chemical doping, 18 carrier adjustment through plasma treatment 19 and carrier injection using uneven metal contacts. 20,21…”